Preformed electrical coil



Aug. 10 1926. 1,595,838

H. w. TURNER PREFORMED ELECTRICAL COIL Filed May 15, 1923 Inventor: Harry \MTurnen BMW Patented Aug. 10, 1926.

UNITED STATES 1,595,838 PATENT OFFICE.

HARRY W. TURNER, BCHNECTADY, NEW YORK, ASQIGHOB '10 mc'rmo comm, A. CORPORATION 0] NEW YORK.

PBEIOBMED ELECTRICAL 0011..

Application filed Kay 15, ms. scram 1n.

My invention relates to reformed electrical coils and has for its 0 ject the provision of a coil which is solidified without the use of auxiliary bonding agents.

In the manufacture of reformed coils of various types for electrica apparatus, it has heretofore been customary to solidify the coil after it has been wound by inserting strips of shellacked aper or fabri between the turns of the coil and then concurrently applying heat and pressure to the coil whereb the shellac was softened and when allowe to cool held the turns of the coil together in a solid mass which had been compacted b the pressure to a predetermined size. ince shellac has a for moisture, this method is obv1ous1y detrimental to the insulating properties of the coil. Thread and tapehave also been used 2 for bonding coils.

In carrying out my invention, I form the coil from a conductor coveredwith a fibrous insulating material which has been impregnated with a suitable non-hygroscopic ad 2 hesive insulating material, such as an ashaltum compound, and then appl suitable eat and preure to the coil where y; the asphaltum com ound softens andcements theconductors o the coil together into a solid compact mass.

For a more complete understanding of my invention reference should be had to the accompanyin drawing in which Fig. 1 shows apparatus or forming electrical coils in accordance with my invention' while Fig. 2 is a section view of a coil embodying my invention.

Referring to the drawing, in one form of my invention the conductor 10 provided with a fabric insulatin covering impregnated with an asph'aiium compound is wound into an electrical coil 11. After being formed, the coil 11 is placed in a suitable clamping device 12 whereby the portions of the coil which are to be inserted in slots or other limited spaces in the apparatus with which the coil is to be used are compressed. At the same time the coil is heated in a suitable manner, for example, by passmg an electric current therethrough b means of conductors 13 and 14 leading mm a suitable source of electrical supply. The heat applied to the coil softens the asphaltum compound with which the fabricmsulatln material on the conductors 1s impregnate great aflinity and the pressure applied OOIiISPMtS the coil to the required dimensions. pon being allowed to cool the asphaltum compound acts as a cement firmly holding the' conductors of the coil together so that the whole is formed 1nto a solid compact mass, as shown in Fig. 2. I have found that the coils should be heated to approximately degrees C. in

order to soften the asphaltum compound sufficiently to permit it to cement the conductors together. -The asphaltum compound is non-hygroscopic so that the coil is offectively sealed against the entrance of moisture.

In the treatment of the conductor 10 the asphaltum compound may and referably is applied to the cotton or other rous covering of the conductor at a relatively hi h temperature, such as about 500 degrees The cotton covered conductor may be passed through a bath of the asphaltum compound maintained at the tern rature referred to. At this temperature t e residual moisture and air are first boiled out of the cotton and then, the viscosity of the normally solid asphaltum compound being relatively low at such high temperatures, the interstices between the fibres of the cotton and even the structure of the fibres are enetrated and filled with the dense aspha tum substance that effectively prevents the reentrance of moisture and air. For the purpose of rendering the surface more repellent to moisture and acids and the covering more Pllable, a coagulable vegetable 011 such as China wood oil, may then be applied whlle the conductor is still hot. Such aninsulated conductor v is described and claimed in m copending application, Serial No. 449,9 filed March 5, 1921.

The use of shellac and other ob ednonable bonding agents for solidifylng the co1lis thus ellminated, whereby the 0011 has better insulating properties and may be comressed into the smallest possible space. I have found, in fact that the conductors of the coil may be bonded together 1 n this manner and compressed to' a proximatel the same dimensions as a simi ar group 0 conductors rovided with untreated cotton coverings. f desired, the coil maybe solidified before removing it from the wmding form b simply applying heat and ressure to it. B y means of my invention, t e process of producing coils is thus greatly simplified and consequently the cost of production is reduced. In short, the coil, after being wound, is solidified simply by applying heat and pressure, no bonding agent, or thread or tape for tying the conductors in place being necessary.

While I have described my invention as embodied in concrete form and as operating in a s cific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various 'modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The method of making an electrical coil which consists in providing a conductor havin a fibrous covering, impregnating said fi rous covering by passing the conductor through a bath of molten asphaltic material heated to a temperature high enough to thinly liquefy it, windin the conductor into a coil, heating the coil t us formed to a temperature high enough to soften the asphaltic material while applying pressure to compact the turns of said coil, and then applying said pressure while the asphaltic ma- 5 fibrous coating is thoroughly impregnated with said asphaltum, windin said conductor into a coil, heating the 0011 thus formed to a temperature of approximately 284 F. to soften said asphaltum, compacting the turns of the coil while the asphaltum is softened, and then maintaining the turns com acted while said asphaltum cools and bar ens whereby said turns are bound together by said asphaltum into a solid mass.

In witness whereof, I have hereunto set my-hand this 11th da of May, 1923.

HAIERY W. TURNER. 

